The inventive concept relates to a semiconductor device. More particularly, the inventive concept relates to a three-dimensional semiconductor device having stacked layers of word lines.
Semiconductor memory devices are becoming more highly integrated to meet consumer demand for high performance and affordable electronic devices. That is, the degree of integration of a semiconductor device is an important factor for determining its price. Therefore, the degree of integration of semiconductor memory devices must be increased to keep costs down. The degree of integration of a typical two-dimensional or planar semiconductor memory device is mainly determined by the area that a unit memory cell of such a device occupies. The ability to scale down the area of a unit memory cell depends on the level of sophistication of techniques for forming fine patterns of features that make up the memory cells. In this respect, high-priced diverse pieces of equipment are required for forming fine patterns. Therefore, there are limitations in the cost savings that can be obtained when increasing the degree of integration of a two-dimensional semiconductor memory device.